From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1A51AC433DF for ; Wed, 20 May 2020 23:40:41 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id C12BE2072C for ; Wed, 20 May 2020 23:40:40 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="uUzCdsJ4" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C12BE2072C Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux-foundation.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 50E6780007; Wed, 20 May 2020 19:40:40 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 498A2900002; Wed, 20 May 2020 19:40:40 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 35F4280007; Wed, 20 May 2020 19:40:40 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0098.hostedemail.com [216.40.44.98]) by kanga.kvack.org (Postfix) with ESMTP id 1B3CF900002 for ; Wed, 20 May 2020 19:40:40 -0400 (EDT) Received: from smtpin16.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id D9BEB181AEF1E for ; Wed, 20 May 2020 23:40:39 +0000 (UTC) X-FDA: 76838719398.16.feet72_5c1327672424 X-HE-Tag: feet72_5c1327672424 X-Filterd-Recvd-Size: 3190 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf20.hostedemail.com (Postfix) with ESMTP for ; Wed, 20 May 2020 23:40:39 +0000 (UTC) Received: from localhost.localdomain (c-73-231-172-41.hsd1.ca.comcast.net [73.231.172.41]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 5825B2072C; Wed, 20 May 2020 23:40:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1590018038; bh=yJQr4N2gMImcjIgh4e+Nb6eX8prUZSgWAz7fgEAtjn8=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=uUzCdsJ4dPUOGOhbWC7K6acCbXeqRHR+0qzMhgjEOxgVke9kEnBa7JF5kx3vHFzK1 2JDsO09C77U5VjEP7YTXkaq7ElxS7VohANm9CztE2bI+QoaSzLs8/SxR/44jb4IDIo fHiF99y61RmpcSRtu67jCykydgbedxtWxWl3l/8Y= Date: Wed, 20 May 2020 16:40:37 -0700 From: Andrew Morton To: Chris Down Cc: Johannes Weiner , Michal Hocko , linux-mm@kvack.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, kernel-team@fb.com Subject: Re: [PATCH] mm, memcg: unify reclaim retry limits with page allocator Message-Id: <20200520164037.e3598bc902e39415f4c263e7@linux-foundation.org> In-Reply-To: <20200520163142.GA808793@chrisdown.name> References: <20200520163142.GA808793@chrisdown.name> X-Mailer: Sylpheed 3.5.1 (GTK+ 2.24.31; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Wed, 20 May 2020 17:31:42 +0100 Chris Down wrote: > Reclaim retries have been set to 5 since the beginning of time in > 66e1707bc346 ("Memory controller: add per cgroup LRU and reclaim"). > However, we now have a generally agreed-upon standard for page reclaim: > MAX_RECLAIM_RETRIES (currently 16), added many years later in > 0a0337e0d1d1 ("mm, oom: rework oom detection"). > > In the absence of a compelling reason to declare an OOM earlier in memcg > context than page allocator context, it seems reasonable to supplant > MEM_CGROUP_RECLAIM_RETRIES with MAX_RECLAIM_RETRIES, making the page > allocator and memcg internals more similar in semantics when reclaim > fails to produce results, avoiding premature OOMs or throttling. > > ... > > --- a/mm/memcontrol.c > +++ b/mm/memcontrol.c > @@ -73,9 +73,6 @@ EXPORT_SYMBOL(memory_cgrp_subsys); > > struct mem_cgroup *root_mem_cgroup __read_mostly; > > -/* The number of times we should retry reclaim failures before giving up. */ hm, what tree is this against? > -#define MEM_CGROUP_RECLAIM_RETRIES 5 > - > /* Socket memory accounting disabled? */ > static bool cgroup_memory_nosocket; > > @@ -2386,7 +2383,7 @@ void mem_cgroup_handle_over_high(void) > unsigned long pflags; > unsigned long nr_reclaimed; > unsigned int nr_pages = current->memcg_nr_pages_over_high; > - int nr_retries = MEM_CGROUP_RECLAIM_RETRIES; > + int nr_retries = MAX_RECLAIM_RETRIES; I can't seem to find a tree in which mem_cgroup_handle_over_high() has a local `nr_retries'.